Ppf
[医][=pellagra preventive factor]抗糙皮病因子，维生素pp
🗣️ 情景例句
Sally and Michael seem to be cut out for each other.
莎莉和迈克看起来很相配。
Never swap (or swop) horses while crossing the stream.
骑渡中流莫换马。（指危难时不宜做大变动）
We have that right here in this report.
在这份报告书内就有。